Surface installation technology appeared in the 1960s, developed a development momentum in the early 1980s, and was widely used in the mid -1990s. Recetishment of the component to make it have a small metal piece or end cover that can directly weld on the PCB surface, rather than the wire through the hole. The component becomes smaller, and the components on both sides of the circuit board are more common than the installation of the hole, allowing smaller PCB components to have higher circuit density. The surface installation is very suitable for highly automation, reducing labor costs and greatly increasing productivity. The components can be installed on the load. The size and weight of the surface installation element can be one -quarter to one -tenth of the hole components, and the passive component is much cheaper. However, the price of semiconductor surface installation devices (SMD) depends more on the chip itself rather than packaging. Compared with larger packaging, there is almost no price advantage. It is much cheaper than SMD equivalent